PSYC23 - Lecture 10 - Mar22.docx

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19 Apr 2012
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LBalaquiao Page 1
PSYC23
LECTURE 10 POLYVAGAL THEORY
March 22nd, 2012
Polyvagal Theory
- 2 distinct branches of the vagus nerve --> different evolutionary stress responses in mammals
o Older system --> primitive --> fight/flight behaviour (immobilization)
o New system --> more evolved --> linked to inhibition of behaviours, communication and
self-soothing
- Opposes the SAM stress response --> Sympathetic-adrenal system
- Vagal tone physiological indicator of stress
Evolutionary Perspective
- Structures
o Dorsal motor nucleus (DMNX) --> older system --> vegetative vagus
Activated when the more evolved branch fails
o Ventrolateral motor nucleus (NA) --> newer system (more evolved) --> smart vagus
o Mylinated vs. Unmylinated --> Some vagal fibers are mylinated and some aren’t -->
Mylinated = more efficient = activated by the newer system (likes to operate
with the smarter one)
- Organization
o Hierarchical --> over the course of evolution we’ve been adding newer and newer
systems --> cumulative effect, integrated into the older system
Newer vagus takes precedence over the older vagus in mammals --> older
system is used when the newer system fails
o Phylogeny recapitulates ontogeny --> you will see things in an egg that look like a more
primitive species --> a lot of similarity in the structures that are developing; all the
different species develop through a lot of the same structures which are repeated
Seeing a new species develop, you can see shapes of the older structures that
are from ancient species; from much earlier primitive species
o Dissolution
Stress and Disease
the first system that fails is always the newer system --> ventrolateral
will go first before the older system
Coping --> each of these functions are associated with a specific function
associated with how we cope in the world
Evolutionary Perspectives: strategies
- Social communication (newer system)
o Facial expression
o Attention (head turning)
o Vocalization
o Listening
- Mobilization (sympathetic nervous system) --> Feeds back to sympathetic adrenal medulla
system
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